1. Field of the Invention
The present invention relates to the abrasive sheet for the clean abrasion of the surface of an object.
2. Description of the Prior Art
In the traditional abrasive sheet as is shown in FIG. 1, abrasive particles 3 such as aluminum oxide (Al.sub.2 O.sub.3), chromium oxide (Cr.sub.2 O.sub.3) or silicon carbide (SiC) are mixed with polyester resin adhesive as a binder 4 and a hardener, the mixture is Stirred up and painted uniformly on a polyester sheet 1 to be dried and hardened. The abrasive sheet produced by this process has a coating of the resin binder 5 on the surface of the abrasive particles in the abrasive layer 2. When polishing silicon wafers for semiconductor device elements with an abrasive sheet as in the prior art, the resin binder 5 coating on the abrasive particles is melted by the heat generated locally by friction and adheres to the wafers. After such thermal melt, carbon impurity adheres to the wafers and is hard to remove. Moreover, hard computer discs are prepared by electro-plating Ni-P on an aluminum base after which iron or chromium is electroplated or sputtered onto the Ni-P. If the surface of the Ni-P is abraded with the traditional abrasive sheet, the binder resin would adhere to the hard discs and degrade their magnetic properties.
The instant invention relates to the discovery that one must remove the binder resin 5 coating from the surface of the abrasive particles of the traditional abrasive sheet in order to eliminate the magnetic degradation or adherence of impurities to the abraded surface.